This invention relates to photonic devices in general, and more particularly to lasers.
Lasers are well known in the art. A laser typically comprises a front mirror and a rear mirror which are disposed so as to establish a reflective cavity therebetween. An active, or gain, region is disposed between the front mirror and the rear mirror. The gain region is constructed so that when the gain region is appropriately stimulated, it will emit light. The rear mirror is typically substantially fully reflective at the lasing wavelength, and the front mirror is typically partially reflective at the lasing wavelength so as to allow a beam of laser light to be emitted therefrom.
As is well known in the art, the gain region may be stimulated by electrical current (xe2x80x9celectrically pumpedxe2x80x9d) or it may be stimulated by light (xe2x80x9coptically pumpedxe2x80x9d).
The present invention is directed to optically pumped lasers and, more particularly, to an improved optically pumped laser having an increased observed, or xe2x80x9cwall-plugxe2x80x9d, efficiency.
The present invention comprises an improved optically pumped laser having increased efficiency.
In one form of the invention, there is provided a laser comprising:
a front mirror and a rear mirror which are disposed so as to establish a reflective cavity therebetween;
a gain region disposed between the front mirror and the rear mirror, the gain region being constructed so that when the gain region is appropriately stimulated by light from a pump laser, the gain region will emit light;
one of the front mirror and the rear mirror is substantially fully reflective at the lasing wavelength, and the other of the front mirror and the rear mirror is partially reflective at the lasing wavelength so as to allow a beam of laser light to be emitted therefrom; and
an intermediate mirror disposed between the rear mirror and the front mirror, at least a portion of the gain region being disposed between the rear mirror and the intermediate mirror, the rear mirror and the intermediate mirror being reflective at the pump wavelength and being spaced from one another so as to cause the pump light to be reflected between the rear mirror and the intermediate mirror so that the pump light will make multiple pumping passes through the gain region, whereby to yield an increased observed, or xe2x80x9cwall-plugxe2x80x9d, efficiency.
In one preferred form of the invention, the gain region is formed by multiple quantum wells (MQW) which act as the intermediate mirror.